Burner system for a furnace or the like using preheated air for combustion



P 4, 1962 H. J. PUGSLEY- ETAL 3,052,456

BURNER SYSTEM FOR A FURNACE oR THE LIKE USING PREHEATED AIR FoRCOMBUSTION Filed Oct. 10, 1957 5 Sheets-Sheet 1 i;

FlG.l. FIG.3.

INVENTORS HUGH J. PUGSLEY a WARREN H. NEViLLE Sept- 4, 19 2 H. J.PUGSLEY ETAL 3,052,456

BURNER SYSTEM FOR A FURNACE OR THE LIKE USING PREHEATED AIR FORCOMBUSTION 5 Sheets-Sheet 2 Filed Oct. 10, 1957 & m Y m Raw W I} O E I.TG NUN I v H mi N H GE Wm nn 0 1 1 1 L Hu United States Patent OfificePatented Sept. 4, 1962 Vania Filed Get. 10, 1957, Ser. No. 689,292Claims. (Cl. 26315) This invention relates to a novel burner system fora furnace or the like of a kind generally adapted to use preheated airfor combustion. More particularly, it pertains to a new relatively lowheadroom, replaceable burner construction for such furnaces and a newmethod for uniformly heating metal ingots or the like in such a furnacewhile inhibiting detrimental flame impingement upon them.

In illustrative prior constructions of, for example, soaking pitfurnaces, such as those of the regenerative type for the heating orreheating of metal work like ingots, the problem of headroom exists inview of the size of such furnaces and the crane and other handling andmill equipment required. Moreover, when burning a relatively low calorieor low pressure fuel gas, the size of the burners required augments theheadroom and construction difficulties. In addition, particularly wherethe burners are located directly in the heating chamber, such chamber asa general rule must be made oversized in order to provide a combustionspace in addition to a heating space, or the risk of harmful flameimpingement upon the work may be encountered in the case of a smallerheating chamber with burners therein. When efforts are made to provide abottom-fired furnace with firing either directly into the heatingchamber or with the burner located outside the heating chamber, slagaccumulations and deposits tend to interfere either with the burner orthe operation thereof. On the other hand, efforts to build burners intothe top of a furnace have encountered practical height limitations,particularly when endeavoring to burn relatively low pressure fuel gas.

The new burner system of our invention is applicable to new soaking pitand other types of furnaces, or it may be used in the modification ofexisting furnaces. Further, devices constructed in accordance with thisinvent-ion provide a removable burner section which neither is subjectto slag deposit difliculty nor is it one which increases the headroomrequired. At the same time, our new burners preferably have a removablesection for adjustment ease and for any maintenance or replacement thatmay be required and such may also be used to provide access to the aircheckers. Moreover, the fuel outlet is preferably located in suchsection which may be made in the shape of a venturi throat so thatrelatively low pressure fuel gases, such as blast furnace gas, may beutilized readily and mixed to better advantage with preheated combustionair. And, provision is made for the meeting of the preheated air andfuel streams at an angle to provide effective mixing and relativelyprompt combustion to aid in the uniform heating of metal work in theheating chamber substantially by combustion gases.

Other objects, features and advantages of our invention will be apparentfrom the following description and the accompanying drawings, which areillustrative of one embodiment only, in which FIGURE 1 is a plan View ofone type of regenerative soaking pit furnace utilizing one embodiment ofour new burner system;

FIGURE 2 is a view in elevation of the construction shown in FIGURE 1taken along line II-II of FIG- URE 1;

FIGURE 3 is a view in plan taken along the line III-III of FIGURE 2;

FIGURE 4 is a detail view taken along line IV-IV of FIGURE 2;

FIGURE 5 is a detail view taken generally along line VV of FIGURE 3; and

FIGURE 6 is a detail view of the portion shown in FIGURE 5 with aremovable section of one embodiment of our new burner in separatedrelation to the balance of the structure.

Referring to the drawings, a regenerative soaking pit 10 is providedwith a refractory lined heating chamber '11. The top of chamber 11 iscovered with a removable cover 12 supported by a carriage 13 which isprovided with controls adapted to lift cover 12 and move it along therails 14 whenever the heating chamber pit 11 is to be opened for theinsertion or removal of metal work like ingots 15 therein, which innumber may substantially fill heating chamber 11. Each new burnerconstruction 16 of our invention is provided with a burner section orport 17 in which combustion occurs and an air port '18 furnishing aconnection between heating chamber 11 and horizontal air checkerwork 19.Each of the horizontal air ducts in the form of checkers 19 respectivelycommunicates with a slag pocket 20 at the base of a stack flue '21having stack checkers 22 therein. As shown, the flues 21 are a part ofIsley-type stacks 23. Furnace 10 is supported on a foundation 24normally below mill floor level by structural steel work which is alsotied into the structural steel binding for the furnace as will beunderstood by those having skill in such matters. The rails 14 for pitcover 12 are also rigidly connected to the structural steel framework offurnace 10.

A fan platform 25 is provided to support a motorblower set 26 whichoperates through a reversing air damper 27 to alternately blow cold airat ambient temperature downwardly through a pipe .28 into the top of therespective stack flue 21 whenever the stack valve 29 in that respectivestack is closed. Conversely, when valve 27 closes off a particular stackflue 21 and the checkers 22 therein, the stack valve 29 for thatparticular stack is open so that air from an induction air fan 30 willrise in an annular chamber 31 to increase the draft operative upon theWaste gases exiting through the respective horizontal checkers 19, thevertical checkerwork 22 and the stack 23 in which such valve 29 is thenopen. In the course of such discharge of waste gases on each side, therefractory in the respective checkers l9 and 22 on that side is heatedso that upon a reversal of flow therethrough, the air from blower 26will be preheated by the time it reaches entry port 18 of the respectiveburner 16 on that firing side at the time being. As shown, when one sideof the furnace is a firing side, the other side is a waste gas dischargeside, and conversely, in furnace 10.

Preferably, the burner passageway or port 17 on each side is directeddownwardly toward the bottom of heating chamber 11 having a hearth 32therein on which the work 15 rests so that hot gases passing intochamber 11 during a firing cycle from a respective side will fill thechamber with heating gases without leaving relatively cool spots oruneven temperature zones between the bottom and the top of the work.Moreover, it will be noted that the axis of each burner 16 including itsburner combustion section '17 is situated so that all the work inheating chamber 11 will be heated by combustion gases and products beingdischarged from the respective burners 16 on the respective sides.Further, such hot gases discharged into heating chamber 11 will be wellmixed and distributed for the maintenance of optimum conditions for theheating of such work 15.

The smaller stack end of the burner ports 17 as compared to theirheating chamber ends and the narrower area of the air passageways orports 18 toward the heating chamber 11 as compared with the area of theends 18a toward the stacks 23 provide, in the embodiment shown, theapproximate limits of a reduced or throat section 33 in each burner 16having a venturi quality. Thereby,

even a fuel gas of relatively low pressure, such as blast furnace gas islikely to be, exiting from a gas outlet 34 in section 33 may be usedreadily and at the same time better mixing with the combustion air willbe obtained. In addition, each fuel gas outlet 34- in the illustratedembodiment is normal to the axis of its respective burner 16. Thereby,such fuel gas upon discharge from outlet 34- will contact axially movingpreheated air and produce a tendency for the line of force or directionof the heating gases to veer toward the adjacent lateral wall 35 on therespective side of heating chamber 11, thereby promoting effectivenessof heating, avoidance of harmful flame impingement upon work 15 anduniformity of temperature obtainable in a heating chamber 11.

The central section 33 of each burner 16, and each burner 16, requirerelatively low head room and are relatively trouble-free because the gasoutlet 34 is on the side with the larger burner bend and cover plateportion 36 accommodated inboard of and between the respective sides offurnace 10 as shown in FIGURE 3.

The removable quality of burner section 33 not only accommodates achange in case a different fuel gas is to be used or a different flameadjustment is desired, but it also facilitates any maintenance orreplacement activity and, further, enables the respective side of thefurnace to be entered for work upon that side such as work on therespective horizontal checkers '19. As shown, each section 33 comprisesa structural frame 37 within which is supportably mounted an outerrefractory layer 38 and an inner refractory layer 39 and provided withan opening therethrough which constitutes gas outlet 34. Outlet 34 maybe made of cast refractory with a fuel gas passage having an approximateright-angled bend portion 40. The lower end of passage 40 is continuedby a flanged pipe section 41 connected in turn to a flange 42 at the endof a fuel gas branch supply pipe 43. Each branch supply pipe 43 makes afurther bend and becomes a horizontal portion 44 of a Y pipingarrangement supplied from a common fuel gas supply pipe 45. Respectivevalves 46 are included in the respective branches 44 of the Y forsuitable control by supplying of fuel gas to the firing side only duringa firing cycle, whether that firing cycle be alternated immediately witha firing cycle on the other side, or whether the furnace 10 is operatedunder firing and dampering conditions.

The structural support 37 of each removable section 33 is also providedwith longitudinally extending binding members 47 and cross supportmembers 48 having sling holes 49 for the raising and lowering of section33 as illustrated respectively in FIGURES and 6, the struc turalovergirding of furnace having a hatch way 59' for such purpose on eachside above each section 33. Likewise, the structural undergirding offurnace 10 is provided with a lower hatchway 51 so that when section 33is to be lowered, as shown in FIGURE 6, the piping can be disconnectedand section 33 can pass through the lower hatchway 51 when suspended,for example, from slings connected to the hook of a crane and extendingthrough upper hatchway 50. When a section 33 is fully lowered as shownin FIGURE 2, it may rest on foundation 24 or it may be lowered onto adolly and moved out from beneath furnace 10 whereupon it can be liftedagain by a crane or other device and taken to another location forstorage or other purpose. Such steps, when taken in reverse, will enablea section 33 to be moved beneath the respective side of furnace 10-below vertically aligned hatchways 50 and 51 on that side so that suchsection 33 can be put into place in a burner 16 needing it.

When each section 33 is in aligned position relative to the rest of itsburner 16, bolts 52 are connected between the members 48 and angles 53to secure such section 33 in place. Preferably, as shown in FIGURES 5and 6, each section 33 is made so as to taper, as viewed from the side,from the bottom to the top to effect appropriate seating and registry ofinner refractory section 39 with corresponding refractory at therespectively adjoining ends of the ports 17 and 18 associated therewith.In addition, an outer refractory ring 38 is cut back from the seatingface of the inner refractory ring to provide peripheral recesses 54which preferably can be filled with a refractory cement when section 33is in place. A split hoop 55 providing inwardly extending asbestos tapering seals 56 adjacent each edge thereof are placed around each jointand the halves of each hoop on each side of section 33 are drawntogether by the bolts 57 completing the gas-tight positioning assemblyof each section 33 in its respective burner 16. After such mounting ofsection 3.3, branch pipe portions 43 and 44 are reconnected by means oftheir respective flanges to the pipe members 41 and 45.

Although the fuel gas outlet 34 in the illustrated embodiment of aburner 16 has its major axis vertical and its plane of discharge atright angles to the axis of section 33, the angle of intersectionbetween such plane and axis may be changed by substituting such asect-ion in which the fuel gas outlet has a different such angle. Inthat way, an adjustment may be provided with facility to correspond to adesired change in the service to be performed or to a desired change inthe flame character.

For example, it would appear, without this invention being limitedthereto, that if such plane of discharge of the fuel gas outlet is swungabout a vertical axis so that fuel gas issues across the combustion airstream from port 18 with a minor direction component counter to the flowof that air, the resulting mixing time would appear to be somewhatreduced and the flame length somewhat shortened. On the other hand, whensuch plane is angled across the combustion air with the issuing fuel gashaving a forward direction component relative, a lengthening effect uponthe flame character would appear to be produci ble. And the angling ofsuch plane may also be made in a skew manner, about an axis other than avertical axis, if desired.

Further, although the illustrated embodiment has the burners 16 inboardof the inner sides of the respective sides of furnace 10, the bend andcover plate portions of the removable section in the burner may beplaced outboard for particular kinds of operation or rearrangements ofthe spatial relation between the work to be heated and the heatingchamber. In addition, each section of a new burner corresponding tosection 33 may be provided with opposed fuel outlets therethrough. Insuch last-mentioned situation, each branch of the fuel gas supply pipewould be divided again to furnish such fuel gas to each one of theopposed outlets. With two fuel gas outlets in each such burner section,control of the direction of the heating gases may also be obtained, ifdesired, by proportioning the respective sizes or angles of discharge ofsuch outlets in one section.

Although the illustrated embodiment has been described in combinationwith a soaking pit furnace utilizing preheated air, it will berecognized by those to whom our invention is disclosed that our newburner system is applicable to various types of furnaces or the likeincluding those utilizing combustion air at ambient temperature withoutpreheating. Further, various modifications may be made in details of theembodiment illustrated, and other embodiments including those describedabove may be provided, without departing from the spirit of ourinvention or the scope of the appended claims.

We claim:

1. A soaking pit furnace or the like with a built-in burner system formetal ingots or the like, comprising, in combination, a heating chamber,a hearth, refractory lined side and end walls and a cover for saidchamber, a pair of laterally spaced generally downwardly directed burnerpassageways in one of said side Walls, said burner passageways extendinggenerally from said hearth to the upper portion of said side wall, saidburner passageways further having an expanding cross section in thedirection of said heating chamber, a removable venturi throat sectionfor each of said burner passageways having a side wall and its interiorin registry with the respective outer ends thereof, an air passagewayfor each of said sections connected to the outer ends thereof andflaring in a direction away from said heating chamber, said burner andair passageways being built into said furnace as an integral partthereof, a combustion air duct in registry with the outer end of each ofsaid air passageways, each said section having a vertical fuel gasoutlet slot extendthrough the side wall of said section to dischargefuel gas generally at right angles to the axis of said section and inintersecting reation thereto, means for holding each said section inupwardly wedged and sealed alignment between the respectively adjoiningends of its respective burner and air passageways, a conduit removablyconnected to each of said outlet slots, means to supply fuel gasalternatively to said sections, and means for preheating and supplyingcombustion air alternatively to the outer ends of each of said airpassageways in timed relation to said supply of fuel gas.

2. In a built-in burner system for a soaking pit furnace or the likehaving a walled heating chamber, apparatus comprising, in combination, aburner passageway adapted to open through a wall of said heating chamberand cooperate with said furnace, said burner passageway adapted toexpand in cross section in the direction of said heating chamber, a fullopening air passageway having an expanding cross section adapted toflare in the direction away from said heating chamber, said passagewaysadapted to be an integral part of said furnace, a removable passagesection of reduced area relative to said passageways positioned betweensaid passageways in graduated registry with said passageways, saidremovable passage section having a side and a fuel gas outlet slotthrough said side at an oblique angle to the axis of said removablepassage section, said slot extending above said axis, means to seal saidsection in said registry, and means for holding said removable passagesection from above in alignment with said passageways.

3. In a furnace or the like for heating metal work, apparatuscomprising, in combination, a heating chamber, a firing passagewayopening into said heating chamber to discharge burning heating gasesthereinto, a burner forming an integral part of said passageway, saidburner having a removable central portion in full registry with saidpassageway, a structural framework for said central portion of saidburner having at least one hatchway below said central portion, meansfor supplying combustion air to the outer end of said passageway, meansfor supplying fuel gas to said passageway through said central portionin a stream the plane of which intersects the axis and a major portionof the interior of said central portion at an abrupt angle to the axisof said central portion, peripheral means for sealing said centralportion in place,

and means for removing said central portion by lower ing it beneath saidpassageway.

4. A burner for a combustion air passage of a furnace or the like forheating metal work and having a heating chamber, said burner having awall and providing a firing passageway adapted to open into a heatingchamber to discharge burning heating gases thereinto, said burner havinga removable central venturi portion, said burner further having anelongated outlet extending through the wall thereof into the interior ofsaid venturi portion, a combustion air passageway in registry with saidventuri portion, means for supplying combustion air through said burnerand fuel gas to the interior of said burner through said venturi portionsubstantially at an oblique angle to the axis of said venturi portion,overhead framework means for suspending said venturi portion to positionit, and means for removing said venturi portion of said burner frombelow to open said combustion air passageway for replacement of aventuri portion of selected character preparatory to further operationthereof in cooperation with said furnace.

5. In a burner system for a soaking pit furnace or the like, apparatuscomprising, in combination, a burner having a central portion of venturishape in longitudinal section, said burner having its central portionremovable, said central portion having a side wall and further havingits edges at the forward and rearward ends thereof lying in upwardlyconverging planes, mating edges in the remaining portions of said burnerfor seating said edges of said central portion, means for mounting saidcentral portion between the mating edges of said burner to align saidcentral portion when said respective mating edges are engaging the edgesof said central portion, and peripherally extending band means forsealing the respective joints between said central portion and theremaining portions of said burner, said central portion having a fueloutlet extending through the side wall thereof into the interior of saidcentral portion, said fuel outlet having its major dimension verticaland its plane of discharge substantially at right angles to the axis ofsaid central portion in intersecting relation thereto, whereby saidremaining portions of said burner may be built into a burner systemadapted to cooperate with a furnace and said central portion may beremoved by lowering the same below the rest of said burner as needed ordesired.

References Cited in the file of this patent UNITED STATES PATENTS936,930 McKennan Oct. 12, 1909 1,102,359 Simens July 7, 1914 1,304,725Aubert May 27, 1919 1,828,830 Crowley Oct. 27, 1931 2,016,458 SchwalbeOct. 8, 1935 2,025,165 Henry Dec. 24, 1935 FOREIGN PATENTS 175,271Austria June 25, 1953 UNITED STATES PATENT OFFICE CERTIFICATE, OFCORRECTION Patent No. 3,052,456 September 4, 1962 Hugh J, Pugsley et a1.

It is hereby certified that error appears in the above numbered petentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 5, line 13, for "extend-" read extending line 16, for "reation"read relation Signed and sealed this 8th day of January 1963.

(SEAL) Attest:

DAVID L. LADD I Commissioner of Patents ERNEST W. SWIDER AttestingOfficer

